Building an Engine Controller

As part of my longstanding planning for having independent back-up services for my property I wanted to develop a standalone power unit for running a generator head with enough capacity to run the well, the house and outbuildings, and some extra capacity. A quick back of the envelop calculation told me I needed about a 20kW generator (40 HP input required using gasoline for fuel). Generators like this can be purchased but I wanted a power unit with the following characteristics. Any new parts needed for it can be readily replaced at low cost and can be held in storage with a small storage volume. It should have multi-fuel capability. It needs to be robust and have a long service life under difficult conditions.

This led me to the idea of using an automotive engine, but to make it work I would have to develop a programmable engine controller. At this stage the system is still classified as experimental and to deploy it would require compliance with various regulatory agencies (EPA, CARB). It should be noted that the system described here is not even close to being suitable for automotive use. It has almost none of the built-in safeguards, error checking, and the real time adaptability to highly variable operating conditions needed for an automotive product.

So with that in mind I came up with a list of requirements for an engine.

1. Has a power output of up to 100 HP (cruise mode 50HP).

2. A 4 cylinder model is compact and powerful enough.

3. Has a robust design. Millions of units sold.

4. Has a straightforward emission reduction scheme. 

I chose a Honda D16 series engine which were manufactured between the late 1980’s and the early 2000’s. These Honda engines have three variable reluctance wheels for generating the signals needed for the appropriate timing sequence located in the distributor. Here’s a picture of the engine I used in this build. I attached the engine to a rolling frame that I fabricated for the purpose. The complete engine cost me $200 from a salvage yard and a complete re-ring kit was $75. The engine controller is shown in the second photo.

To bring this post to a fitting and proper conclusion I’ll offer a “proof of life.” In the video you can see the engine running with the as built controller. All of the steps that I took to make it work will be described in subsequent posts.